Hypervisor function sets

ABSTRACT

A method, system, and apparatus for informing a plurality of operating systems, each assigned to a separate partition within a logically partitioned data processing system, of which functions, provided by a hypervisor for creating and enforcing separation of the logical partitions, are available for use by the operating systems is provided. In a preferred embodiment, the hypervisor includes a plurality of function sets. Each function set includes a list of functions that may be called by any one of the operating systems to perform tasks for the operating systems while maintaining separation between each of the logical partitions. The hypervisor informs each of the plurality of operating systems of an enabled function set. Functions identified within the enabled function set are enabled for use by each of the plurality of operating systems and functions not identified within the enabled function set are disabled for use by each of the plurality of operating systems.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is related to co-pending U.S. patent applicationSer. No. 09/589,663 entitled “HYPERVISOR AS A SET OF SERVICES” filedJun. 8, 2000 and to U.S. patent application Ser. No. 09/589,665 entitled“DMA WINDOWING” filed Jun. 8, 2000 and issued Sep. 30, 2003 as U.S. Pat.No. 6,629,162. The content of the above-mentioned commonly assigned,co-pending U.S. patent applications are hereby incorporated herein byreference for all purposes.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates generally to the field of computerarchitecture and, more specifically, to methods and systems for managingresources among multiple operating system images within a logicallypartitioned data processing system.

2. Description of Related Art

A logical partitioning option (LPAR) within a data processing system(platform) allows multiple copies of a single operating system (OS) ormultiple heterogeneous operating systems to be simultaneously run on asingle data processing system platform. A partition, within which anoperating system image runs, is assigned a non-overlapping sub-set ofthe platform's resources. These platform allocable resources include oneor more architecturally distinct processors with their interruptmanagement area, regions of system memory, and I/O adapter bus slots.The partition's resources are represented by its own open firmwaredevice tree to the OS image.

Each distinct OS or image of an OS running within the platform areprotected from each other such that software errors on one logicalpartition cannot affect the correct operation of any of the otherpartitions. This is provided by allocating a disjoint set of platformresources to be directly managed by each OS image and by providingmechanisms for ensuring that the various images cannot control anyresources that have not been allocated to it. Furthermore, softwareerrors in the control of an OS's allocated resources are prevented fromaffecting the resources of any other image. Thus, each image of the OS(or each different OS) directly controls a distinct set of allocableresources within the platform.

One method that has been developed to create and maintain separationbetween the partitions within the data processing system is the use of afirmware component referred to as a hypervisor in the RS/6000 dataprocessing system. The RS/6000 is a product and trademark ofInternational Business Machines Corporation of Armonk, N.Y. Thisfirmware component performs many functions and services for the variousoperating system images running within the logically partitioned dataprocessing system.

As the software and hardware are improved over time, the library ofservices offered by the firmware component expands. The OS images mustbe made aware of these changes. Furthermore, as various options areselected by various implementations, or options are enabled or disabledby user policy, the OS images must also be made aware of these changesas well. Currently, there is no method for providing this information tothe various OS images such that they are aware of which functions areavailable from the firmware component on a given platform at a giventime. Thus, it is desirable to have a mechanism for making the OS imageswithin a logically partitioned system aware of which functions areavailable to it through the firmware component.

SUMMARY OF THE INVENTION

The present invention provides a method, system, and apparatus forinforming a plurality of operating systems, each assigned to a separatepartition within a logically partitioned data processing system, ofwhich functions, provided by a hypervisor for creating and enforcingseparation of the logical partitions, are available for use by theoperating systems. In a preferred embodiment, the hypervisor includes aplurality of function sets. Each function set includes a list offunctions, that may be called by any one of the operating systems toperform tasks for the operating systems while maintaining separationbetween each of the logical partitions. The hypervisor informs each ofthe plurality of operating systems of an enabled function set. Functionsidentified within the enabled function set are enabled for use by eachof the plurality of operating systems and functions not identifiedwithin the enabled function set are disabled for use by each of theplurality of operating systems.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. The invention itself, however, as well asa preferred mode of use, further objectives and advantages thereof, willbest be understood by reference to the following detailed description ofan illustrative embodiment when read in conjunction with theaccompanying drawings, wherein:

FIG. 1 depicts a pictorial representation of a distributed dataprocessing system in which the present invention may be implemented;

FIG. 2, a block diagram of a data processing system in accordance withthe present invention is illustrated;

FIG. 3 depicts a block diagram of a data processing system, which may beimplemented as a logically partitioned server, in accordance with thepresent invention;

FIG. 4 depicts a block diagram of a logically partitioned platform inwhich the present invention may be implemented;

FIG. 5 depicts an exemplary hypervisor function set table in accordancewith the present invention;

FIG. 6 depicts a flowchart illustrating an exemplary process forproviding an operating system with a list of hypervisor function callsavailable on a platform in accordance with the present invention; and

FIG. 7 depicts a flowchart illustrating an exemplary method for updatinga list of function sets within a platform in accordance with the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference now to the figures, and in particular with reference toFIG. 1, a pictorial representation of a distributed data processingsystem is depicted in which the present invention may be implemented.

Distributed data processing system 100 is a network of computers inwhich the present invention may be implemented. Distributed dataprocessing system 100 contains network 102, which is the medium used toprovide communications links between various devices and computersconnected within distributed data processing system 100. Network 102 mayinclude permanent connections, such as wire or fiber optic cables, ortemporary connections made through telephone connections.

In the depicted example, server 104 is connected to hardware systemconsole 150. Server 104 is also connected to network 102, along withstorage unit 106. In addition, clients 108, 110 and 112 are alsoconnected to network 102. These clients, 108, 110 and 112, may be, forexample, personal computers or network computers. For purposes of thisapplication, a network computer is any computer coupled to a networkthat receives a program or other application from another computercoupled to the network. In the depicted example, server 104 is alogically partitioned platform and provides data, such as booth files,operating system images and applications, to clients 108-112. Hardwaresystem console 150 may be a laptop computer and is used to displaymessages to an operator from each operating system image running onserver 104, as well as to send input information, received from theoperator, to server 104. Clients 108, 110 and 112 are clients to server104. Distributed data processing system 100 may include additionalservers, clients, and other devices not shown. Distributed dataprocessing system 100 also includes printers 114, 116 and 118. A client,such as client 110, may print directly to printer 114. Clients, such asclient 108 and client 112, do not have directly attached printers. Theseclients may print to printer 116, which is attached to server 104, or toprinter 118, which is a network printer that does not require connectionto a computer for printing documents. Client 110, alternatively, mayprint to printer 116 or printer 118, depending on the printer type andthe document requirements.

In the depicted example, distributed data processing system 100 is theInternet, with network 102 representing a worldwide collection ofnetworks and gateways that use the TCP/IP suite of protocols tocommunicate with one another. At the heart of the Internet is a backboneof high-speed data communication lines between major nodes or hostcomputers consisting of thousands of commercial, government, education,and other computer systems that route data and messages. Of course,distributed data processing system 100 also may be implemented as anumber of different types of networks such as, for example, an intranetor a local area network.

FIG. 1 is intended as an example and not as an architectural limitationfor the processes of the present invention.

With reference now to FIG. 2, a block diagram of a data processingsystem in accordance with the present invention is illustrated. Dataprocessing system 200 is an example of a hardware system console, suchas hardware system console 150 depicted in FIG. 1. Data processingsystem 200 employs a peripheral component interconnect (PCI) local busarchitecture. Although the depicted example employs a PCI bus, other busarchitectures, such as Micro Channel and ISA, may be used. Processor 202and main memory 204 are connected to PCI local bus 206 through PCIbridge 208. PCI bridge 208 may also include an integrated memorycontroller and cache memory for processor 202. Additional connections toPCI local bus 206 may be made through direct component interconnectionor through add-in boards. In the depicted example, local area network(LAN) adapter 210, SCSI host bus adapter 212, and expansion businterface 214 are connected to PCI local bus 206 by direct componentconnection. In contrast, audio adapter 216, graphics adapter 218, andaudio/video adapter (A/V) 219 are connected to PCI local bus 206 byadd-in boards inserted into expansion slots. Expansion bus interface 214provides a connection for a keyboard and mouse adapter 220, modem 222,and additional memory 224. In the depicted example, SCSI host busadapter 212 provides a connection for hard disk drive 226, tape drive228, CD-ROM drive 230, and digital video disc read only memory drive(DVD-ROM) 232. Typical PCI local bus implementations will support threeor four PCI expansion slots or add-in connectors.

An operating system runs on processor 202 and is used to coordinate andprovide control of various components within data processing system 200in FIG. 2. The operating system may be a commercially availableoperating system, such as OS/2, which is available from InternationalBusiness Machines Corporation. “OS/2” is a trademark of InternationalBusiness Machines Corporation. An object-oriented programming system,such as Java, may run in conjunction with the operating system,providing calls to the operating system from Java programs orapplications executing on data processing system 200. Instructions forthe operating system, the object-oriented operating system, andapplications or programs are located on a storage device, such as harddisk drive 226, and may be loaded into main memory 204 for execution byprocessor 202.

Those of ordinary skill in the art will appreciate that the hardware inFIG. 2 may vary depending on the implementation. For example, otherperipheral devices, such as optical disk drives and the like, may beused in addition to or in place of the hardware depicted in FIG. 2. Thedepicted example is not meant to imply architectural limitations withrespect to the present invention. For example, the processes of thepresent invention may be applied to multiprocessor data processingsystems.

With reference now to FIG. 3, a block diagram of a data processingsystem, which may be implemented as a logically partitioned server, suchas server 104 in FIG. 1, is depicted in accordance with the presentinvention. Data processing system 300 may be a symmetric multiprocessor(SMP) system including a plurality of processors 301, 302, 303, and 304connected to system bus 306. For example, data processing system 300 maybe an IBM RS/6000, a product of International Business MachinesCorporation in Armonk, N.Y. Alteratively, a single processor system maybe employed. Also connected to system bus 306 is memory controller/cache308, which provides an interface to a plurality of local memories360-363. I/O bus bridge 310 is connected to system bus 306 and providesan interface to I/O bus 312. Memory controller/cache 308 and I/O busbridge 310 may be integrated as depicted.

Data processing system 300 is a logically partitioned data processingsystem. Thus, data processing system 300 may have multiple heterogeneousoperating systems (or multiple instances of a single operation system)running simultaneously. Each of these multiple operating systems mayhave any number of software programs executing within it. Dataprocessing system 300 is logically partitioned such that different I/Oadapters 320-321, 328-329, 336-337, and 346-347 may be assigned todifferent logical partitions.

Thus, for example, suppose data processing system 300 is divided intothree logical partitions, P1, P2, and P3. Each of I/O adapters 320-321,328-329, and 336-337, each of processors 301-304, and each of localmemories 360-364 is assigned to one of the three partitions. Forexample, processor 301, memory 360, and I/O adapters 320, 328, and 329may be assigned to logical partition P1; processors 302-303, memory 361,and I/O adapters 321 and 337 may be assigned to partition P2; andprocessor 304, memories 362-363, and I/O adapters 336 and 346-347 may beassigned to logical partition P3.

Each operating system executing within data processing system 300 isassigned to a different logical partition. Thus, each operating systemexecuting within data processing system 300 may access only those I/Ounits that are within its logical partition. Thus, for example, oneinstance of the Advanced Interactive Executive (AIX) operating systemmay be executing within partition P1, a second instance (image) of theAIX operating system may be executing within partition P2, and a Windows2000™ operating system may be operating within logical partition P1.Windows 2000 is a product and trademark of Microsoft Corporation ofRedmond, Wash.

Peripheral component interconnect (PCI) Host bridge 314 connected to I/Obus 312 provides an interface to PCI local bus 315. A number of TerminalBridges 316-317 may be connected to PCI bus 315. Typical PCI busimplementations will support four Terminal Bridges for providingexpansion slots or add-in connectors. Each of Terminal Bridges 316-317is connected to a PCI/I/O Adapter 320-321 through a PCI Bus 318-319.Each I/O Adapter 320-321 provides an interface between data processingsystem 300 and input/output devices such as, for example, other networkcomputers, which are clients to server 300. Only a single I/O adapter320-321 may be connected to each terminal bridge 316-317. Each ofterminal bridges 316-317 is configured to prevent the propagation oferrors up into the PCI Host Bridge 314 and into higher levels of dataprocessing system 300. By doing so, an error received by any of terminalbridges 316-317 is isolated from the shared buses 315 and 312 of theother I/O adapters 321, 328-329, and 336-337 that may be in differentpartitions. Therefore, an error occurring within an I/O device in onepartition is not “seen” by the operating system of another partition.Thus, the integrity of the operating system in one partition is noteffected by an error occurring in another logical partition. Withoutsuch isolation of errors, an error occurring within an I/O device of onepartition may cause the operating systems or application programs ofanother partition to cease to operate or to cease to operate correctly.

Additional PCI host bridges 322, 330, and 340 provide interfaces foradditional PCI buses 323, 331, and 341. Each of additional PCI buses323, 331, and 341 are connected to a plurality of terminal bridges324-325, 332-333, and 342-343, which are each connected to a PCI I/Oadapter 328-329, 336-337, and 346-347 by a PCI bus 326-327, 334-335, and344-345. Thus, additional I/O devices, such as, for example, modems ornetwork adapters may be supported through each of PCI I/O adapters328-329, 336-337, and 346-347. In this manner, server 300 allowsconnections to multiple network computers. A memory mapped graphicsadapter 348 and hard disk 350 may also be connected to I/O bus 312 asdepicted, either directly or indirectly. Hard disk 350 may be logicallypartitioned between various partitions without the need for additionalhard disks. However, additional hard disks may be utilized if desired.

Those of ordinary skill in the art will appreciate that the hardwaredepicted in FIG. 3 may vary. For example, other peripheral devices, suchas optical disk drives and the like, also may be used in addition to orin place of the hardware depicted. The depicted example is not meant toimply architectural limitations with respect to the present invention.

With reference now to FIG. 4, a block diagram of an exemplary logicallypartitioned platform is depicted in which the present invention may beimplemented. The hardware in logically partitioned platform 500 may beimplemented as, for example, server 300 in FIG. 3. Logically partitionedplatform 400 includes partitioned hardware 430, hypervisor 410, andoperating systems 402-408. Operating systems 402-408 may be multiplecopies of a single operating system or multiple heterogeneous operatingsystems simultaneously run on platform 400.

Partitioned hardware 430 includes a plurality of processors 432-438, aplurality of system memory units 440-446, a plurality of input/output(I/O) adapters 448-462, and a storage unit 470. Each of the processors442-448, memory units 440-446, and I/O adapters 448-462 may be assignedto one of multiple partitions within logically partitioned platform 400,each of which corresponds to one of operating systems 402-408.

Hypervisor 410, implemented as firmware, performs a number of functionsand services for operating system images 402-408 to create and enforcethe partitioning of logically partitioned platform 400. Firmware is“hard software” stored in a memory chip that holds its content withoutelectrical power, such as, for example, read-only memory (ROM),programmable ROM (PROM), erasable programmable ROM (EPROM), electricallyerasable programmable ROM (EEPROM), and non-volatile random accessmemory (non-volatile RAM).

Hypervisor 410 provides a secure direct memory access (DMA) window, perIOA, such as, for example, IOA 328 in FIG. 3, on a shared I/O bus, suchas, for example, I/O bus 312 in FIG. 3, into the memory resourcesallocated to its associated OS image, such as, for example, OS image 402in FIG. 4. In one embodiment, as implemented within an RS/6000 PlatformArchitecture, the hypervisor makes use of two existing hardwaremechanisms. These hardware mechanisms are called the translation controlentry (TCE) facility and the DMA range register facility of an EADS PCIto PCI bridge chip. In this embodiment, these two hardware mechanismsare placed under the control of the hypervisor.

When platform 400 is initialized, a disjoint range of I/O bus DMAaddresses is assigned to each of IOAs 448-462 for the exclusive use ofthe respective one of IOAs 448-462 by hypervisor 410. Hypervisor 410then configures the EADS range register (not shown) facility to enforcethis exclusive use. Hypervisor 410 then communicates this allocation tothe owning one of OS images 402-408. Hypervisor also initializes allentries in the IOA associated section of the TCE table to point to areserved page per image that is owned by an OS image, such thatunauthorized accesses to memory by one of OS images 402-408 will notcorrupt or rob data from a neighboring one of OS images 402-408.

When an owning one of OS images 402-408 requests to map some of itsmemory for a DMA operation, it makes a call to the hypervisor 410including parameters indicating the IOA, the memory address range, andthe associated I/O bus DMA address range to be mapped. The hypervisor410 checks that the IOA and the memory address range are allocated tothe owning one of OS images 402-408. The hypervisor 410 also checks thatthe I/O bus DMA range is within the range allocated to the IOA. If thesechecks are passed, the hypervisor 410 performs the requested TCEmapping. If these checks are not passed, the hypervisor rejects therequest.

Hypervisor 410 also may provide the OS images 402-408 running inmultiple logical partitions each a virtual copy of a console andoperator panel. The interface to the console is changed from anasynchronous teletype port device driver, as in the prior art, to a setof hypervisor firmware calls that emulate a port device driver. Thehypervisor 410 encapsulates the data from the various OS images onto amessage stream that is transferred to a computer 480, known as ahardware system console.

Hardware system console 480 is connected directly to logicallypartitioned platform 400 as illustrated in FIG. 4, or may be connectedto logically partitioned platform through a network, such as, forexample, network 102 in FIG. 1. Hardware system console 480 may be, forexample, a desktop or laptop computer, and may be implemented as dataprocessing system 200 in FIG. 2. Hardware system console 480 decodes themessage stream and displays the information from the various OS images402-408 in separate windows, at least one per OS image. Similarly,keyboard input information from the operator is packaged by the hardwaresystem console, sent to logically partitioned platform 400 where it isdecoded and delivered to the appropriate OS image via the hypervisor 410emulated port device driver associated with the then active window onthe hardware system console 480.

In order to prevent instruction fetch errors in hypervisor 410 fromaffecting OS images 402-408 and the rest of platform 400, two copies ofthe hypervisor 410 instructions are loaded into the memory of platform400. A hypervisor 410 instruction fetch error occurs when one of theprocessors 432-438 is executing hypervisor 410 instructions and, afterfetching the next instruction from one of memories 440-446 containingthe hypervisor 410 instructions, detects that there is an error in theinstruction. For example, the error could be the result of theinstruction having been stored in a bad memory location, such that theinstruction has become corrupted. Such an error in the instructionresults in a machine check interrupt and the processor, on occurrence ofsuch an interrupt, is unable to determine what instruction it shouldexecute next. In the prior art, such an occurrence would result ineither a need to reboot the entire system, thus interfering with thecontinuous operation of OS images 402-408, or extra redundancy bits forthe entire system memory plus more complex encoding and decoding logicwere utilized to recover from the error. Allowing for the necessity ofrebooting the entire system could result in the loss of data forapplications executing in one of OS images 402-408, which isunacceptable and should be avoided if at all possible. Utilizing theextra redundancy bits along with more complex encoding and decodinglogic impairs the speed and performance of platform 400.

Hypervisor 410 also provides other functions and services to each ofoperating systems 402-408. Some of these functions and services are notoptional, such as the virtual console and operator panel describedabove. However, other services provided by the hypervisor 410 may beoptional, allowing the platform administrator to make policy decisionswith regard to options, that while generally useful, the administratormay wish to disable due to, for example, security concerns.Alternatively, optional features allow for expanded functionality overtime, allowing new features to be introduced on new machines while thesame operating system seamlessly runs on old machines without the newfunction.

Below, in Table 1, is an exemplary table of function sets and theirmandatory/optional status. The hcall-pft functions manipulate the pageframe table for processor virtual address translation. The hcall-tcefunction set manipulates the Direct Memory Access (DMA) facilities usedby the IO devices as described in U.S. patent application Ser. No.09/589,665 (IBM Docket No. AUS990941US1) entitled “DMA Windowing” filedon Jun. 8, 2000, and issued Sep. 30, 2003 as U.S. Pat. No. 6,629,162.The hcall sprg0, hcall-dabr and hcall-asr functions manipulate internalprocessor registers which may themselves be optional. The hcall-debugand hcall-perf function sets provide services needed by debuggers andperformance monitor routines. The hcall-term function set provides thefunction described in the virtual terminal invention disclosure. Finallyhcall-dump provides facilities to allow an OS to do a dump of theHypervisor data areas for platform debug.

TABLE 1 Mandatory Function Set Yes hcall-pft Yes hcall-tce Yeshcall-sprg0 No - Only if DABR hcall-dabr Exists Yes hcall-copy No - Onlyif Istar hcall-asr Processors Yes hcall-debug Yes hcall-term Yeshcall-perf No - Only if enabled by hcall-dump HSC (default disabled)

To make certain features available, hypervisor 410 provides a list offunction sets. Each function set includes one or more hypervisorfunction cells. Once a function set has been selected by platform 400,all function calls contained within the function set must be madeavailable to each of OSs 402-408.

In one embodiment, the OS is made aware of the services in the functionset by being passed a parameter called a “property” in a structure thatit receives at boot time. This property contains the list of thefunction set names, outlined above, that are available for it to use.The OS is expected to only make those requests that are specified in theproperty list, however, if the OS should make some other call that isnot specified as being supported, the hypervisor will return an errormessage to the OS.

As a new service or function call for hypervisor 410 is provided, asystem architect adds these new services and function calls to a newfunction set to include the newly available services and function calls.This is typically performed by the vendor prior to delivering a newupdated hypervisor version to a platform.

Those of ordinary skill in the art will appreciate that the hardware andsoftware depicted in FIG. 4 may vary. For example, more or fewerprocessors and/or more or fewer operating system images may be used thanthose depicted in FIG. 4. The depicted example is not meant to implyarchitectural limitations with respect to the present invention.

With reference now to FIG. 5, an exemplary hypervisor function set tableis depicted in accordance with the present invention. Hypervisorfunction set table 500 includes a plurality of function sets 501-510under a heading of “function set names” 520. Each of function sets501-510 contains a list of hypervisor function calls under the headingof “functions” 530 available within that particular one of function sets501-510.

With reference now to FIG. 6, a flowchart illustrating an exemplaryprocess for providing an operating system with a list of hypervisorfunction calls available on a platform is depicted in accordance withthe present invention. To begin, the hypervisor, such as hypervisor 410in FIG. 4, receives a request to configure the hypervisor function callsfor the platform, such as, for example, platform 400 (step 602). Thehypervisor presents the user (typically the system administrator), suchas through a window display on hardware system console 480 in FIG. 4,with a list of function set options available (step 604). The availablefunction sets may be Function Sets 501-510 depicted in FIG. 5. In oneembodiment, the displayed list may contain only the function set nameswith additional information about each function set available through aselectable hyperlink. In another embodiment, the list may contain thename of each function set along with information detailing thedifferences between the function set, but not displaying each functioncall available with each particular function set. In yet anotherembodiment, the entire function call list for each function set may bedisplayed to the user.

Once the user has selected a function set for use with the platform, thehypervisor receives the user selected option (step 606) and stores theselection (step 608) in a storage device within the platform, such as,for example, hard disk 350 in FIG. 3. Each time a new operating systemimage is started on the platform, the hypervisor provides the newlystarted OS image with the user selected function set, which includes alist of available hypervisor function calls enabled for the OS image(step 610).

With reference now to FIG. 7, a flowchart illustrating an exemplarymethod for updating a list of function sets within a platform isdepicted in accordance with the present invention. To update a list offunction sets with newly introduced function sets, a new version of thehypervisor firmware is loaded onto the platform (step 702). The platformis then rebooted (step 704) and the hypervisor reports any new functionsets it may support to the OSs on this OS boot (step 706). An old levelof an OS that does not understand how to use the new function set willignore it and use the same subset of the hypervisor's functions that itdid prior to the update. A newer level of OS that had been capable ofusing the new function but had been restricted by a lack of hypervisorfirmware support in the old level of the hypervisor will, after theupdate, see the availability of the new functions and proceed to usethem.

It is important to note that while the present invention has beendescribed in the context of a fully functioning data processing system,those of ordinary skill in the art will appreciate that the processes ofthe present invention are capable of being distributed in the form of acomputer readable medium of instructions and a variety of forms and thatthe present invention applies equally regardless of the particular typeof signal bearing media actually used to carry out the distribution.Examples of computer readable media include recordable-type media suchas a floppy disc, a hard disk drive, a RAM, and CD-ROMs andtransmission-type media such as digital and analog communications links.

The description of the present invention has been presented for purposesof illustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the art. Theembodiment was chosen and described in order to best explain theprinciples of the invention, the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

1. A logically partitioned data processing system, comprising: aplurality of operating systems, each assigned to a separate one of aplurality of logical partitions; a hypervisor for creating and enforcingseparation between each of the plurality of logical partitions; whereinthe hypervisor includes a plurality of selectable function sets, eachfunction set including a list of hypervisor function calls that areprovided by the hypervisor which may be called by any one of theplurality of operating systems to get said hypervisor to perform tasksfor the calling one of the plurality of operating systems whilemaintaining separation between each of the plurality of logicalpartitions, said hypervisor receiving a selection of one of saidplurality of function sets; said selected one of said plurality offunction sets being enabled; the hypervisor informs each of theplurality of operating systems of an enabled function set, functioncalls included within the enabled function set being enabled for use byeach of the plurality of operating systems and function calls notincluded within the enabled function set being disabled for use by eachof the plurality of operating systems.
 2. The logically partitioned dataprocessing system as recited in claim 1, wherein the enabled functionset from the plurality of function sets may be changed such that adifferent one of the plurality of function sets becomes the enabledfunction set.
 3. The logically partitioned data processing system asrecited in claim 1, wherein additional function sets may be added to theplurality of function sets as additional function calls are added to theplurality of function calls provided by the hypervisor.
 4. The logicallypartitioned data processing system as recited in claim 1, wherein thehypervisor is implemented as firmware.
 5. The logically partitioned dataprocessing system as recited in claim 1, wherein each of the pluralityof function sets comprises a different group of the plurality offunction calls.
 6. The logically partitioned data processing system asrecited in claim 1, wherein optional function calls are omitted from atleast one of the plurality of function sets.
 7. A method of identifyinghypervisor function calls that are currently available for execution bya hypervisor in a logically partitioned data processing system, themethod comprising: assigning each one of a plurality of operatingsystems to a separate one of a plurality of logical partitions; creatingand enforcing, by said hypervisor, separation between each of theplurality of logical partitions; providing, by said hypervisor, aplurality of selectable function sets, each function set including alist of function calls that are provided by the hypervisor that can becalled by any one of the plurality of operating systems to get saidhypervisor to perform tasks for the calling one of the plurality ofoperating systems while maintaining separation between each of theplurality of logical partitions; receiving, by said hypervisor, aselection of one of said plurality of function sets; enabling saidselected one of said plurality of function sets; informing, by saidhypervisor, each one of the plurality of operating systems of an enabledfunction set, function calls included within the enabled function setbeing enabled for use by each one of the plurality of operating systemsand function calls not included within the enabled function set beingdisabled for use by each one of the plurality of operating systems,wherein hypervisor function calls that are currently available forexecution are identified.
 8. The method as recited in claim 7, furthercomprising: responsive to loading a new version of the hypervisor, thenew version of the hypervisor containing additional function calls,reporting the additional function calls to each operating system uponre-initialization.
 9. The method as recited in claim 8, wherein there-initialization of each operating system is performed by a reboot. 10.The method as recited in claim 7, wherein the operating system image isinitialized by booting.
 11. The method as recited in claim 7, whereinthe hypervisor is implemented as firmware.
 12. The method according toclaim 7, further comprising: receiving a selection of said one of saidplurality of function sets from a platform included within said dataprocessing system.
 13. The method according to claim 7, furthercomprising: during booting of each one of said plurality of operatingsystems, passing a parameter to each one of said plurality of operatingsystems that identifies said selected one of said plurality of functionsets.
 14. The method according to claim 7, further comprising: receivingsaid selection of said one of said plurality of function sets from auser.
 15. A computer program product in a computer readable media foruse in a data processing system for identifying hypervisor functioncalls that are currently available for execution by a hypervisor in alogically partitioned data processing system, the computer programproduct comprising: instructions for assigning each one of a pluralityof operating systems to a separate one of a plurality of logicalpartitions; instructions for creating and enforcing, by said hypervisor,separation between each of the plurality of logical partitions;instructions for providing, by said hypervisor, a plurality ofselectable function sets, each function set including a list of functioncalls that are provided by the hypervisor that can be called by any oneof the plurality of operating systems to get said hypervisor to performtasks for the calling one of the plurality of operating systems whilemaintaining separation between each of the plurality of logicalpartitions; instructions for receiving, within said hypervisor, aselection of one of said plurality of function sets; instructions forenabling said selected one of said plurality of function sets;instructions for informing, by said hypervisor, each one of theplurality of operating systems of an enabled function set, functioncalls included within the enabled function set being enabled for use byeach one of the plurality of operating systems and function calls notincluded within the enabled function set being disabled for use by eachone of the operating systems, wherein hypervisor function calls that arecurrently available for execution are identified.
 16. The computerprogram product as recited in claim 15, further comprising:instructions, responsive to loading a new version of the hypervisor, thenew version of the hypervisor containing additional function calls, forreporting the additional function calls to each operating system uponre-initialization.
 17. The computer program product as recited in claim16, wherein the re-initialization of each operating system is performedby a reboot.
 18. The computer program product as recited in claim 15,wherein the operating system image is initialized by booting.
 19. Thecomputer program product as recited in claim 15, wherein the hypervisoris implemented as firmware.
 20. A system for identifying hypervisorfunction calls that are currently available for execution by ahypervisor in a logically partitioned data processing system, the systemcomprising: means for assigning each one of a plurality of operatingsystems to a separate one of a plurality of logical partitions; meansfor creating and enforcing, by said hypervisor, separation between eachof the plurality of logical partitions; means for providing, by saidhypervisor, a plurality of selectable function sets, each function setincluding a list of function calls that are provided by the hypervisorthat can be called by any one of the plurality of operating systems toperform tasks for the calling one of the plurality of operating systemswhile maintaining separation between each of the plurality of logicalpartitions; means for receiving a selection of one of said plurality offunction sets; means for enabling said selected one of said plurality offunction sets; means for informing, by said hypervisor, each one of theplurality of operating systems of an enabled function set, functioncalls included within the enabled function set being enabled for use byeach one of the plurality of operating systems and function calls notincluded within the enabled function set being disabled for use by eachone of the operating systems, wherein hypervisor function calls that arecurrently available for execution are identified.
 21. The system asrecited in claim 20, further comprising: means, responsive to loading anew version of the hypervisor, the new version of the hypervisorcontaining additional function calls, for reporting the additionalfunction calls to each operating system upon re-initialization.
 22. Thesystem as recited in claim 21, wherein the re-initialization of eachoperating system is performed by a reboot.
 23. The system as recited inclaim 20, wherein the operating system image is initialized by booting.24. The system as recited in claim 20, wherein the hypervisor isimplemented as firmware.